WO2015161203A1 - Functionalized nanostructures and devices including photovoltaic devices - Google Patents

Functionalized nanostructures and devices including photovoltaic devices Download PDF

Info

Publication number
WO2015161203A1
WO2015161203A1 PCT/US2015/026379 US2015026379W WO2015161203A1 WO 2015161203 A1 WO2015161203 A1 WO 2015161203A1 US 2015026379 W US2015026379 W US 2015026379W WO 2015161203 A1 WO2015161203 A1 WO 2015161203A1
Authority
WO
WIPO (PCT)
Prior art keywords
substituted
group
carbon nanostructure
isobenzofulvene
polymer
Prior art date
Application number
PCT/US2015/026379
Other languages
English (en)
French (fr)
Inventor
Timothy M. Swager
Vladimir Bulovic
Ggoch Ddeul HAN
Andrea MAURANO
Riccardo Po
Andrea Pellegrino
Original Assignee
Massachusetts Institute Of Technology
Eni S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Massachusetts Institute Of Technology, Eni S.P.A. filed Critical Massachusetts Institute Of Technology
Priority to US15/305,076 priority Critical patent/US10672988B2/en
Priority to EP15780617.5A priority patent/EP3132451A4/en
Priority to CN201580032244.0A priority patent/CN106463196B/zh
Publication of WO2015161203A1 publication Critical patent/WO2015161203A1/en

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
    • H10K85/211—Fullerenes, e.g. C60
    • H10K85/215—Fullerenes, e.g. C60 comprising substituents, e.g. PCBM
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/04—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of carbon-silicon compounds, carbon or silicon
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/152—Fullerenes
    • C01B32/156—After-treatment
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/06—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances
    • H01B1/12—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of other non-metallic substances organic substances
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
    • H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/20—Carbon compounds, e.g. carbon nanotubes or fullerenes
    • H10K85/221—Carbon nanotubes
    • H10K85/225—Carbon nanotubes comprising substituents
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/30—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/50—Photovoltaic [PV] devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/80—Constructional details
    • H10K30/81—Electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/151—Copolymers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/549—Organic PV cells

Definitions

  • compositions and devices including nano structures comprising isobenzofulvene species and/or indane species are provided, as well as related methods.
  • BHJ bulk heterojunction
  • PCE power conversion efficiency
  • Covalently functionalized fullerenes such as PCBM ([6,6]-phenyl-C6i- butyric acid methyl ester) and ICBA (Indene-C6o Bisadducts) are widely used n-type molecules and have been shown to generate promising PCEs in combination with suitable polymer counterparts.
  • ICBA open-circuit voltages
  • Voc open-circuit voltages
  • HOMO D -LUMO A A: acceptor, D: donor
  • novel acceptors with high LUMO levels have been designed and investigated for high Voc devices.
  • the device comprises a composition comprising a carbon nanostructure comprising a substituted isobenzofulvene group or a substituted indane group; and at least one electrode in electrochemical communication with the composition.
  • the device is a photovoltaic device comprising an electron donor material; and an electron acceptor material in contact with the electron donor material and comprising a substituted isobenzofulvene group or a substituted indane group.
  • Methods for fabricating a device comprising reacting a carbon nanostructure with an isobenzofulvene group precursor to produce a functionalized carbon nanostructure comprising a substituted isobenzofulvene group; and arranging the functionalized carbon nanostructure in electrochemical communication with an electrode.
  • compositions comprising carbon nanostructures are also provided.
  • the carbon nanostructure comprises a fused network of aromatic rings, optionally comprising a border at which the fused network terminates, wherein the carbon nanostructure comprises the following structure,
  • A comprises the fused network of aromatic rings of the carbon nanostructure
  • R 1 -R 8 can be the same or different and are hydrogen, hydroxyl, halo, alkyl, heteroalkyl, alkenyl, heteroalkenyl, aryl, heteroaryl, or heterocycle, any of which is optionally substituted, provided that at least one of R x -R 8 is not hydrogen; or, R 3 and R 4 are joined together to form an optionally substituted ring.
  • FIG. 1 shows the structure of a carbon nanostructure appended with an isobenzofulvene species and/or indane species.
  • FIG. 2 shows the synthesis of (a) C 6 o substituted with an isobenzofulvene group
  • FIG. 3 shows cyclic voltammograms for (a) PCBM, IBF-Mono, and IBF-Bis; (b)
  • PCBM PCBM, IBF-Mono, and IBF-Ep; and (c) PCBM, IBF-Bis, IBF-Bis-Epl, and IBF-Bis- Epl (under nitrogen, 0.1M Bu 4 NPF 6 in toluene/acetonitrile (4: 1), Pt (WE), Pt wire (CE), Ag/AgNOs (RE), scan rate 0.1 V/s, Fc/Fc + internal standard E 1/2 at 0.20 V).
  • FIG. 4 shows the UV-Vis absorption spectra for (a) PCBM (2.4 x 10-5 M), IBF- Mono (2.2 x 10-5 M), IBF-Bis (2.4 x 10-5 M), and IBF-Ep (2.3 x 10-5 M); and (b)
  • PCBM (2.4 x 10-5 M), IBF-Bis-Epl (2.4 x 10-5 M) and IBF-Bis-Ep2 (2.2 x 10-5 M), in CHC1 3 .
  • FIG. 5 shows the molecular orbital (MO) energy level diagrams for (a) various C 60 adducts such as IBF-Mono, IBF-Bis, and IBF-Ep and (b) IBF-Bis, IBF-Bis-Epl, and IBF-Bis-Ep2.
  • MO molecular orbital
  • FIG. 6 shows (a) the current density as a function of applied voltage for the fullerenes in BHJ architecture for solar cells with P3HT as an electron donor, compared to conventional P3HT:PCBM, and (b) a box plot of the VOC values obtained from the devices in (a) where the whiskers were the 10th to 90th percentile and the box was the 25th and 75th percentile containing a median and average (dotted line).
  • FIG. 7 shows (a) steady-state spectral UV-vis absorption spectra and (b) steady- state spectral photoluminescence emission of thin films containing various fullerene adducts; and (c) spectral external quantum efficiency (EQE) and (d) spectral internal quantum efficiency (IQE) of devices incorporating various fullerene adducts.
  • EQE spectral external quantum efficiency
  • IQE spectral internal quantum efficiency
  • FIG. 8 shows atomic force microscopy tomography images of the devices analyzed in this study at (a) 1 micron and (b) 10 micron scale.
  • FIG. 9 shows transient photocurrents at short circuit of P3HT:PCBM
  • FIG. 10 shows recombination lifetime as a function of the averaged excess charge density measured with transient photovoltage and photocurrent (TPV/TPC).
  • Embodiments described herein provide functionalized carbon nanostructures for use in various devices, including photovoltaic devices (e.g., solar cells). Devices including such materials may exhibit increased efficiency, increased open circuit potential, high electron/hole mobility, and/or low electrical resistance.
  • photovoltaic devices e.g., solar cells
  • Devices including such materials may exhibit increased efficiency, increased open circuit potential, high electron/hole mobility, and/or low electrical resistance.
  • carbon nanostructures having one or more functional groups capable of enhancing the electronic properties of the carbon nanostructures are provided.
  • the composition may include functional groups which are selected and positioned to interact with a portion of the carbon nanostructure and/or another component in contact with the carbon nanostructure, such as a polymer, thereby enhancing one or more properties of the carbon nanostructure.
  • the carbon nanostructure may include a functional group positioned in close physical proximity to the pi-system of the carbon nanostructure, resulting in favorable cofacial pi-orbital interactions which affect the electronic properties of the carbon nanostructure.
  • the functional group may affect (e.g., increase, decrease) the electron affinity of the carbon nanostructure.
  • the functional group may affect (e.g., increase, decrease) the energy level of the lowest unoccupied molecular orbital (LUMO) of the carbon nanostructure.
  • the carbon nanostructure may be a fullerene (e.g., C 6 o) which includes an olefin functional group attached to and positioned in close proximity to the surface of the fullerene, allowing for cofacial pi-orbital interactions between the olefin and the fullerene. Such interactions may effectively increase the LUMO level of the fullerene and increase open-circuit voltage of device.
  • the electron affinity and/or LUMO energy level of the carbon nanostructure may be tuned by further functionalization (e.g., epoxidation) of the olefin functional group, as described more fully below.
  • compositions comprising carbon nanostructures substituted with a substituted isobenzofulvene groups and/or a substituted indane group are provided.
  • the carbon nanostructure includes one or more substituted isobenzofulvene groups.
  • the isobenzofulvene group may include a carbon- carbon double bond and/or a phenyl group positioned relative to the surface of the carbon nanostructure such that pi-pi interactions may occur between the carbon nanostructure and the carbon-carbon double bond and/or the phenyl group.
  • the carbon nanostructure includes one or more substituted indane groups.
  • the carbon nanostructure includes a combination of substituted isobenzofulvene and substituted indane groups.
  • the carbon nanostructure may include a fused network of aromatic rings, optionally comprising a border at which the fused network terminates, such that the substituted isobenzofulvene group and/or a substituted indane group is attached to the network via at least one ring atom of the network.
  • the substituted isobenzofulvene group and/or a substituted indane group is attached to the network via two ring atoms of the network (e.g., two adjacent ring atoms of the network).
  • the substituted isobenzofulvene group and/or a substituted indane group may be directly bonded to the carbon nanostructure, i.e., a ring atom of the substituted isobenzofulvene group and/or a substituted indane group may form a covalent bond with a ring atom of the network of aromatic rings.
  • two ring atoms of the at least one substituted isobenzofulvene group and/or at least one substituted indane group form covalent bonds with two ring atoms of the network of aromatic rings.
  • a substituted isobenzofulvene group and/or a substituted indane group is not directly bonded to the carbon nanostructure if there is another atom or group (e.g., a methylene group, an aryl group, a metal atom, etc.) present that links the substituted isobenzofulvene group and/or a substituted indane group to the carbon nanostructure.
  • another atom or group e.g., a methylene group, an aryl group, a metal atom, etc.
  • the substituted isobenzofulvene group and/or a substituted indane group may be selected such that a portion of substituted isobenzofulvene group and/or a substituted indane group is arranged in a substantially fixed position relative to the carbon nano structure. That is, a portion of the substituted isobenzofulvene group and/or a substituted indane group may not freely rotate such that the portion can be positioned at a range of different distances from the carbon nano structure. In some cases, a portion of the substituted isobenzofulvene group and/or a substituted indane group may be positioned in a substantially fixed position about 3 Angstroms (e.g., 3.1 Angstroms) from the carbon nanostructure. For example, a fullerene may be fused to a substituted isobenzofulvene group via two bonds, such that a portion of the substituted
  • isobenzofulvene group e.g., a phenyl ring
  • the portion includes a carbon-carbon double bond, which is positioned in sufficient proximity to the carbon nanostructure to interact with the carbon nanostructure via cofacial pi-interactions.
  • the ring atoms of the substituted isobenzofulvene group and/or a substituted indane group may be positioned in a substantially fixed position relative to the carbon nanostructure, but one or more substituents of the substituted isobenzofulvene group and/or a substituted indane group may freely rotate.
  • a carbon nanostructure substituted with a substituted isobenzofulvene group and/or a substituted indane group may exhibit an increase in LUMO energy level of about 20 meV, 50 meV, about 100 meV (e.g., 90 meV), about 150 meV, about 200 meV, about 250 meV (e.g., 260 meV), about 300 meV, about 350 meV, about 400 meV, or about 450 meV, relative to the LUMO energy level of ([6,6]-phenyl-C 6 i-butyric acid methyl ester) (PCBM).
  • PCBM LUMO energy level
  • the composition comprising the functionalized carbon nanostructures may be provided as a solution.
  • the composition may be provided as a solid or a substantially solid substance (e.g., gel).
  • the composition may be formed as a solid-state film.
  • the film may be formed using methods known in the art, including solution coating, ink jet printing, spin coating, dip coating, spray coating, and the like.
  • at least a portion of the film may have a thickness between about 1 nm and about 1 mm, or between about 1 nm and about 500 um, or between about 1 nm and about 500 nm, or between about 100 nm and about 500 nm, or between about 100 nm and about 300 nm.
  • At least a portion of the film has a thickness of 75 nm.
  • Film thickness may be determined by methods known in the art, including ellipsometry. In some cases, the film thickness may be measured using ellipsometry on films, such as films prepared on silicon substrates.
  • compositions comprising a functionalized carbon nanostructure as described herein may be incorporated into a wide range of applications, including photovoltaic devices (e.g., solar cells), batteries, capacitors, transistors, catalyst systems, or chemical or biological sensors.
  • the composition may be arranged in connection with an external source of energy, one or more electrodes, an electrolyte, separator materials, sample inlets and outlets, sample cells, substrates, detectors, power sources, and/or other device components suitable for a particular application.
  • the composition may be arranged to be in electrochemical communication with an electrode material, such that a potential or voltage may be applied to the composition.
  • the composition may be used as a photoactive material in a device.
  • the composition may be arranged to be exposed to a sample suspected of containing an analyte, such as a chemical or biological analyte.
  • the composition may be included in an electrode material for electrocatalysis.
  • the device is a photovoltaic cell, such as a solar cell.
  • Photovoltaic cells generally include a photoactive material containing an electron acceptor/electron donor material, and at least two electrodes (e.g., an anode and a cathode).
  • the device may also include a substrate (e.g., on which to form the photoactive material, anode, and/or cathode), electron-blocking and/or electron-transporting membrane(s), circuitry, a power source, and/or an electromagnetic radiation source.
  • the substrate e.g., on which to form the photoactive material, anode, and/or cathode
  • electron-blocking and/or electron-transporting membrane(s) e.g., on which to form the photoactive material, anode, and/or cathode
  • circuitry e.g., on which to form the photoactive material, anode, and/or cathode
  • the device may also include a substrate (e.g
  • composition including the functionalized carbon nanostructures may be used as an electron acceptor material or an n-type material in a photovoltaic device.
  • a photovoltaic device may include a photoactive material comprising an electron acceptor material that includes functionalized carbon nanostructures as described herein in contact with an electron donor material, where the photoactive material is placed in contact with two electrodes.
  • the electron donor and electron acceptor materials may be arranged to form a bulk heterojunction and to have sufficient donor-acceptor interfacial area to favor exciton dissociation and efficient transport of separated charges to the respective electrodes.
  • the electron donor material may be a polymer.
  • the polymer may be a conducting polymer.
  • the conducting polymer is a semiconducting polymer.
  • conducting polymers include polyaniline, polythiophene, polypyrrole, polyphenylene, polyarylene, poly(bisthiophene phenylene), a ladder polymer, poly(arylene vinylene), poly(arylene ethynylene), metal derivatives thereof, or substituted derivatives thereof.
  • the polymer may be a low band gap polymer, such as a polymer including one or more heteroaryl groups.
  • the polymer contains a nitrogen- containing heteroaryl. Examples of heteroaryl groups include triazoles, carbazoles, pyrroles, thiadiazoles, benzotriazoles, benzothiadiazoles, benzodithiophenes, or imidazoles.
  • polymers suitable for use as electron donor materials include poly(3-hexylthiophene) (P3HT), poly(benzo[l,2-b:4,5-b']dithiophene- thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD), poly( ⁇ 4,8-bis[(2- ethylhexyl)oxy]benzo[l,2-b:4,5-b']dithiophene-2,6-diyl ⁇ ⁇ 3-fluoro-2-[(2- ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl ⁇ ) (PTB7), poly[2,6-(4,4-bis-(2- ethylhexyl)-4H-cyclopenta [2,1- ⁇ ;3,4- ⁇ '] dithiophene)-alt-4,7(2,l,3-benzothiadiazole)] (PCPDTBT), and poly ⁇
  • the electron donor material may include an electron-donating species and the electron acceptor material may include an electron-withdrawing species, where the electron-donating species and electron- withdrawing species interact.
  • the electron donor material may include a fullerene species comprising an epoxide group and the electron acceptor material may include a low band gap polymer comprising heterocyclyl group, such as a triazole, wherein the epoxide ground and the triazole group interact with one another via, for example, hydrogen bonding, electrostatic interactions, or other interactions.
  • the electron donor material may include an electron- withdrawing species and the electron acceptor material may include an electron- donating species, where the electron-withdrawing species and electron-donating species interact.
  • a functional group which creates a dipole associated the functionalized carbon nanostructure, and/or facilitates a dipolar organization at the interface between the electron donor material and the electron acceptor material.
  • introduction of a polar group e.g., an oxygen- containing group such as an epoxide
  • introduction of a polar group within the functionalized carbon nanostructure (e.g., fullerene) may enhance transport of charge away from such an interface, resulting in a slower rate of recombination.
  • a polar group e.g., an oxygen- containing group such as an epoxide
  • introduction of a polar group e.g., an oxygen- containing group such as an epoxide
  • the functionalized carbon nanostructure e.g., fullerene
  • Such properties may be advantageous in optimizing VOC, charge transfer (Jsc and/or PCE for photovoltaic devices.
  • the photovoltaic device may further comprise electrodes and/or other
  • the photovoltaic device may be exposed to light using methods known to those of ordinary skill in the art.
  • the light may interact with the photoactive material, causing electrons to be transferred from the electron donor material (e.g., polymer) to the n-type material or electron-acceptor material (e.g., functionalized carbon nanostructure).
  • the electrons in the n-type material can be transported to the anode and the corresponding holes can be transported to the cathode via the hole donor material.
  • the components of the photovoltaic device may be arranged in various configurations.
  • the electron acceptor material may be dispersed in clusters throughout the electron donor material.
  • the clusters may be substantially surrounded by an electron donor material.
  • the electron donor material and electron acceptor material may be randomly dispersed with respect to one another, thereby forming a heterogeneous material.
  • the electron donor material and/or the electron acceptor material can be formed as layers of films.
  • an array of different devices with different compositions and different morphologies or different layouts can be used.
  • the device may be configured such that the electron donor/electron acceptor materials are placed between two electrodes, e.g., a cathode and an anode.
  • the components of the device may be arranged to form a "normal" or “conventional” solar cell structure, i.e., where positive current may flow from the cathode of the solar cell device to an external circuit.
  • indium tin oxide ( ⁇ ) is arranged as a cathode in a "normal" solar cell structure, though other materials may also be used as a cathode.
  • ITO cathode/electron blocking layer/active layer/hole blocking layer/ Al anode An example of a "normal" solar cell structure is ITO cathode/electron blocking layer/active layer/hole blocking layer/ Al anode, where the active layer contains an electron acceptor material and/or an electron donor material as described herein.
  • the device structure may be as follows: glass/ITO/PEDOT:PSS/P3HT:fullerene/Ca/Al.
  • the components of the device may be arranged to form an "inverted" solar cell structure.
  • positive current may flow from an external circuit into the anode of the solar cell device.
  • ITO is arranged as an anode in an "inverted” solar cell structure.
  • the structure may include the following arrangement: ITO/hole blocking layer/active layer/electron blocking layer/ Ag or Au, where Ag or Au are the cathodes and the active layer contains an electron acceptor material and/or an electron donor material as described herein.
  • the device structure may be as follows
  • Photovoltaic devices described herein may exhibit enhanced performance relative to previous photovoltaic devices.
  • incorporation of a carbon nanostructure containing a substituted isobenzofulvene group and/or a substituted indane group may raise the LUMO level of the electron acceptor material relative to an unsubstituted carbon nanostructure, thereby enhancing open-circuit potential (VOC) and efficiency of the device.
  • VOC open-circuit potential
  • the photovoltaic device exhibits a higher efficiency relative to an essentially identical photovoltaic device lacking the substituted isobenzofulvene group and/or substituted indane group, under essentially identical conditions.
  • the photovoltaic device exhibits an efficiency that is about 1%, about 3%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or, in some cases, about 100% greater than that of an essentially identical photovoltaic device lacking the substituted isobenzofulvene group and/or substituted indane group, under essentially identical conditions.
  • exposure to “conditions” or a “set of conditions” may comprise, for example, exposure to a particular temperature, pH, solvent, chemical reagent, type of atmosphere (e.g., nitrogen, argon, oxygen, etc.), source of external energy (e.g., voltage), or the like. Some embodiments may involve a set of conditions involving exposure to a source of external energy.
  • the source of energy may comprise electromagnetic radiation, electrical energy, sound energy, thermal energy, or chemical energy.
  • the "conditions" may involve exposure to a particular potential, solvent, chemical species, and/or functional group precursor.
  • Comparison of a first device and a second device under "essentially identical conditions” means placing the first and second devices under the substantially the same temperature, pH, solvent, chemical reagent, type of atmosphere, source of external energy, etc., for substantially the same period of time and observing the performance or behavior of the first and second devices.
  • Devices are not placed under "essentially identical conditions” if, for example, a first device is exposed to a higher temperature, a different pH, a different chemical reagent, etc., or perhaps the same chemical reagent but at a different concentration, than a second device.
  • the photovoltaic device exhibits a higher open circuit potential relative to an essentially identical photovoltaic device lacking the substituted isobenzofulvene group or substituted indane group, under essentially identical conditions. In some embodiments, the photovoltaic device exhibits an open circuit potential that is about 1%, about 3%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%, or, in some cases, about 100% greater than that of an essentially identical photovoltaic device lacking the substituted isobenzofulvene group or substituted indane group, under essentially identical conditions.
  • the substituted isobenzofulvene group or substituted indane group is substituted with an electron-donating group. In some embodiments, the substituted isobenzofulvene group or substituted indane group is substituted with an electron- withdrawing group.
  • the carbon nanostructure contains the following structure,
  • A comprises the fused network of aromatic rings of the carbon nanostructure
  • R 1 -R 8 can be the same or different and are hydrogen, hydroxyl, halo, alkyl, heteroalkyl, alkenyl, heteroalkenyl, aryl, heteroaryl, or heterocycle, any of which is optionally substituted, provided that at least one of R x -R 8 is not hydrogen; or, R 3 and R 4 are joined together to form an optionally substituted ring.
  • R 1 and R 2" are each independently alkyl.
  • R 5 -R 8 are each hydrogen.
  • R 1 - R 8 are not hydroxyl.
  • R 1 -R8 are not halo.
  • R 1 -R 8 are the same or different and are hydrogen, alkyl, heteroalkyl, alkenyl, heteroalkenyl, aryl, heteroaryl, or heterocycle, any of which is optionally substituted, provided that at least one of R x -R 8 is not hydrogen; or, R 3 and R 4 are joined together to form an optionally substituted ring.
  • the carbon nanostructure has a structure as in Formula
  • the carbon nanostructure has a structure as in
  • R 1 , R2 , and R 5 -R 8 can be the same or different and are hydrogen, hydroxyl, halo, alkyl, heteroalkyl, alkenyl, heteroalkenyl, aryl, heteroaryl, or heterocycle, any of which is optionally substituted, and R 3 and R 4 are joined together to form an epoxide ring.
  • the carbon nanostructure has a structure as in Formula (II), wherein R 1 and R 2 are each methyl, R 3 and R 4 are joined together to form an epoxide ring, and R 5 -R 8 are each hydrogen.
  • the carbon nanostructure is a fullerene, such as C 36 , C50, C 6 o, C 61 , C70, C76, C84, a metal derivative thereof, a substituted derivative thereof, or a mixture thereof.
  • a device may include a fullerene appended with a substituted isobenzofulvene group and a polymeric electron donor material. Cofacial pi- interactions may occur between the olefin moiety and/or the phenyl moiety of the substituted isobenzofulvene group with the fused network of aromatic rings on the surface of the fullerene, resulting in significantly elevated LUMO energy levels and higher VOCs relative to those obtained from a similar device which includes PCBM instead of the fullerene containing the substituted isobenzofulvene group.
  • a device may include a fullerene appended with an indane group comprising an epoxide moiety. Such a device may exhibit a relatively high IQE, and hence an improved JSC. In some cases, such devices may exhibit a slower
  • the carbon nanostructure may be, for example, a fullerene, a nanotube, graphene, or graphite.
  • the carbon nanostructure is a single- walled nanotube.
  • the carbon nanostructure is a multi- walled nanotube, such as a double-walled nanotube.
  • the carbon nanostructure is a fullerene.
  • the carbon nanostructure comprises one, two, three, four, five, or six substituted isobenzofulvene groups and/or substituted indane groups.
  • the carbon nanostructure can include any number of optionally substituted isobenzofulvene and/or a substituted indane groups, and those of ordinary skill in the art would be capable of selecting the appropriate reaction conditions to produce a carbon nanostructure having the desired number of substituted
  • the nanostructure includes an indane group substituted with at least one alkyl group (e.g., substituted at the 2-position of the indane moiety).
  • the carbon nanostructure is a fullerene that includes one, two, or three isobenzofulvene groups substituted with at least one (e.g., two) alkyl group.
  • the carbon nanostructure includes is a fullerene that includes one two or three isobenzofulvene groups substituted with at least one (e.g., two) alkyl group.
  • the terms “substituted” and “functionalized” are given their ordinary meaning in the art and refer to species which have been altered (e.g., reacted) such that a new functional group (e.g., atom or chemical group) is bonded to the species.
  • the functional group may form a bond to one atom (e.g., a ring atom) of the carbon nanostructure.
  • the functional group may be fused to the carbon nanostructure via two atoms (e.g., two ring atoms) of the carbon nanostructure.
  • Carbon nanostructures may be functionalized with isobenzofulvene moieties using a variety of methods.
  • the method may involve reaction of a carbon nanostructure with an isobenzofulvene group precursor to produce a functionalized carbon
  • the reaction involves a pericyclic reaction such as a Diels- Alder reaction.
  • the isobenzofulvene group precursor, or an intermediate produced by the isobenzofulvene group precursor may act as a diene and the carbon nanostructure (e.g., fullerene) may serve as a dienophile in a Diels-Alder reaction.
  • the reaction may be performed in the presence of an additive that may enhance and/or facilitate the pericyclic reaction.
  • Some embodiments may involve formation of an isobenzofulvene group precursor in situ, followed by addition of the carbon nanostructure to form a carbon nanostructure functionalized with an isobenzofulvene group (e.g., a substituted isobenzofulvene group).
  • the isobenzofulvene group precursor may be a species that serves as a diene in a Diels-Alder reaction with a carbon nanostructure.
  • the isobenzofulvene group precursor prepared in situ has the following structure,
  • R 1 , R2 , and R 5 -R 8 can be the same or different and are hydrogen, hydroxyl, halo, alkyl, heteroalkyl, alkenyl, heteroalkenyl, aryl, heteroaryl, or heterocycle, any of which is optionally substituted, provided that at least one of R 1 , R2 , and R 5 -R 8 is not hydrogen.
  • FIG. 2A shows an illustrative embodiment in which an isobenzofulvene group precursor, which may act as a diene, is produced in situ via the reaction between 9- isopropylidenebenzonorborna-diene and 3,6-di-2-pyridyl-l,2,4,5-tetrazine, followed by electrocyclic fragmentation of N 2 .
  • Addition of C 6 o, a dienophile, to the reaction mixture may produce C 6 o adduct comprising a substituted isobenzofulvene group.
  • the Diels-Alder reaction may be performed at low temperature (e.g., 0 °C to room temperature).
  • the reactions may be performed in the presence of one or more solvents, including organic solvents.
  • the products may be isolated using known techniques, such as column chromatography.
  • the carbon nanostructure may include one or more functional groups which may be further reacted to attach additional groups to the carbon nanostructure.
  • the substituted isobenzofulvene and/or substituted indane group(s) may serve as a precursor for a wide range of additional functional groups that may be incorporated onto (e.g., bonded to) the carbon nanostructure. This may allow for the facile tailoring of various properties of carbon nanostructures, including stability, solubility, miscibility, biocompatibility, optical properties, electronic properties (e.g., electron affinity), binding properties, surface affinities, and the like.
  • a carbon nanostructure may be functionalized with various alkyl groups, which may increase the solubility of the carbon nanostructure in organic solvents such as chloroform, dichloromethane, and toluene.
  • the functionalization of carbon nanostructures may be readily reversible, which can be useful in applications such as exfoliation or deaggregation of carbon nanostructures.
  • the functionalized carbon nanostructure may be further reacted to attach additional functional groups and/or replace existing functional groups with new atoms or groups. That is, at least one atom or chemical group of the functionalized carbon nanostructure may be replaced with a second, different atom or chemical group, or at least one atom or chemical group of the functionalized carbon nanostructure may be linked to a second, different atom or chemical group.
  • the carbon nanostructure may be first functionalized with a substituted isobenzofulevene group, which may be further reacted, for example, via a double bond of the isobenzofulevene group.
  • Further functionalization or reaction of the functionalized carbon nanostructure may be performed using various chemical reactions known in the art, where reaction components are selected to react together in a manner that produces a desired chemical bond.
  • reaction components are selected to react together in a manner that produces a desired chemical bond.
  • Such reactions are known in the art, for example, in “Advanced Organic Chemistry” by Carey and Sundberg and in “Advanced Organic Chemistry” by Jerry March, the contents of which are incorporated herein by reference.
  • reactions that may be useful in methods described herein include substitutions, eliminations, additions, condensations, aromatic substitutions, pericyclic reactions and cycloadditions, photochemical reactions, thermal reactions, Wittig reactions, metal-catalyzed reactions, rearrangement reactions, reductions, oxidations, and the like.
  • a functionalized carbon in some cases, a functionalized carbon
  • nanostructure may be reacted via heating, exposure to acid or base, or via a
  • the method may involve reacting the functionalized carbon nanostructure under conditions which result in the conversion of the substituted isobenzofulvene group to a substituted indane group.
  • the functionalized carbon nano structure may be exposed to a peroxide-containing reagent, resulting in epoxidation of the substituted isobenzofulvene group.
  • peroxide-containing reagents include meta-chloroperoxybenzoic acid (mCPBA).
  • Chemical reactions may be selected to be compatible with (e.g., inert to) other functional groups that may be present during the reaction.
  • the chemical reaction may be selected to be compatible with carbon nanostructures.
  • protecting groups may be used to prevent reaction at sites other than the desired reactive site.
  • the phrase "protecting group" as used herein refers to temporary substituents which protect a potentially reactive functional group from undesired chemical transformations. Examples of such protecting groups include esters of carboxylic acids, silyl ethers of alcohols, and acetals and ketals of aldehydes and ketones, respectively.
  • the field of protecting group chemistry has been reviewed (Greene, T. W.; Wuts, P. G. M. Protective Groups in Organic Synthesis, 2nd ed.; Wiley: New York, 1991).
  • protecting groups may impart other beneficial characteristics, including improved solubility of a compound in a particular solvent.
  • the set of conditions may include, for example, a particular temperature, pH, solvent, chemical reagent, type of atmosphere (e.g., nitrogen, argon, oxygen, etc.), the presence or absence of water, the relative ratio of reagents used, reaction time, and/or the like.
  • the chemical stability of the reaction components may affect the selection of reaction conditions. In some cases, it may be advantageous to perform the reaction under substantially moisture-free conditions. In some cases, the reaction may
  • Electron donor materials used in photovoltaic devices may include a conducting polymer.
  • Conducting polymers refer to extended molecular structures comprising a conjugated backbone (e.g., pi-conjugated backbone, sigma-conjugated backbone, etc.), where "backbone” refers to the longest continuous bond pathway of the polymer.
  • Polymers may also include oligomers.
  • conducting polymers include at least one portion along which electron density or electronic charge can be conducted, where the electronic charge is delocalized.
  • p-orbitals of one monomer have sufficient overlap with p-orbitals of an adjacent monomer such that electronic charge may be delocalized.
  • a conjugated pi-backbone includes a plane of atoms directly participating in the conjugation, wherein the plane arises from a preferred arrangement of p-orbitals to maximize p-orbital overlap, thus maximizing conjugation and electronic conduction.
  • the conducting polymer may be a
  • conducting polymers include polyaniline, polythiophene, polyp yrrole, polyphenylene, polyarylene, poly(bisthiophene phenylene), a ladder polymer, poly(arylene vinylene), poly(arylene ethynylene), metal derivatives thereof, or substituted derivatives thereof.
  • the conducting polymer may be polythiophene or a substituted derivative thereof.
  • Poly(thiophenes) generally contain the repeating unit:
  • R a and R b can be the same or different and each can independently be hydrogen, alkyl, heteroalkyl aryl, heteroaryl, arylalkyl, arylheteroalkyl, heteroarylalkyl, each optionally substituted; and n can be any integer between 2 and 100,000,000.
  • R a , R b , R c , and R d can be the same or different and each can independently be hydrogen, alkyl, heteroalkyl aryl, heteroaryl, arylalkyl, arylheteroalkyl, heteroarylalkyl, each optionally substituted; and n and m can be the same or different and can be any integer between 2 and 100,000,000.
  • poly(thiophenes) include alkyl- substituted poly(thiophene)s (e.g., poly(3-hexylthiophene), poly(3,4- ethylenedioxythiophene) (PEDOT), etc.).
  • the polymer is poly(3-hexylthiophene).
  • the electron donor material may also comprise a low band gap polymer.
  • the substrate may comprise an electrically conductive material.
  • the substrate may comprise a material coated with an electrically conductive material, such that the photoactive material may be formed in contact with the electrically conductive material.
  • materials suitable for use as a substrate include, but are not limited to, metals, such as nickel, chromium, gold, molybdenum, tungsten, platinum, titanium, aluminum, copper, palladium, silver, other metals and/or metal compounds, alloys thereof, intermetallic compounds thereof, and the like. Other materials may also be useful, including indium tin oxide ( ⁇ ).
  • the substrate may also comprise a flexible material, such as plastics (e.g., polymer), polymer films, flexible glass films, metal foil, paper, woven materials, combinations thereof, and the like.
  • the substrate may be a flexible material coated with an electrically conductive material, for example.
  • the substrate may be prepared, for example, by one of a number of micromachining methods known to those skilled in the art. Examples of such methods include, for instance, photofabrication, etching, electrodischarge machining, electrochemical machining, laser beam machining, wire electrical discharge grinding, focused ion beam machining, micromilling, micro- ultrasonic machining, and micropunching.
  • the dimensions of the substrate may be any length, width, and thickness that is desired for a particular end use and may be rectangular, circular or otherwise shaped.
  • fullerene is given its ordinary meaning in the art and refers to a substantially spherical molecule generally comprising a fused network of five- membered and/or six-membered aromatic rings.
  • C 6 o is a fullerene which mimics the shape of a soccer ball.
  • the term fullerene may also include molecules having a shape that is related to a spherical shape, such as an ellipsoid. It should be understood that the fullerene may comprise rings other than five- and six-membered rings. In some embodiments, the fullerene may comprise seven-membered rings, or larger.
  • Fullerenes may include C 36 , C50, C 6 o, C 61 , C70, C76, C84, metal derivatives thereof, substituted derivatives thereof, and the like.
  • the device may include a mixture of different fullerenes.
  • Fullerenes may also comprise individual atoms, ions, metals, nanoparticles, and/or clusters in the inner cavity of the fullerene, i.e., may be endohedral fullerenes.
  • a non-limiting example of a substituted fullerene which may be used as the n-type material is phenyl-C6i -butyric acid methyl ester.
  • the term "electron-donating group,” as used herein, refers to a functionality which draws electrons to itself less than a hydrogen atom would at the same position. Exemplary electron-donating groups include alkyl, amino, methoxy, and the like.
  • electron- withdrawing group is recognized in the art and as used herein means a functionality which draws electrons to itself more than a hydrogen atom would at the same position.
  • exemplary electron- withdrawing groups include nitro, cyano, carbonyl groups (e.g., aldehydes, ketones, esters, etc.), sulfonyl, trifluoromethyl, and the like.
  • react refers to the formation of a bond between two or more components to produce a stable, isolable compound.
  • a first component and a second component may react to form one reaction product comprising the first component and the second component joined by a covalent bond.
  • reacting may also include the use of solvents, catalysts, bases, ligands, or other materials which may serve to promote the occurrence of the reaction between component(s).
  • a “stable, isolable compound” refers to isolated reaction products and does not refer to unstable intermediates or transition states.
  • alkyl refers to the radical of saturated aliphatic groups, including straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl substituted cycloalkyl groups, and cycloalkyl substituted alkyl groups.
  • the alkyl groups may be optionally substituted, as described more fully below. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, 2-ethylhexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and the like.
  • Heteroalkyl groups are alkyl groups wherein at least one atom is a heteroatom (e.g., oxygen, sulfur, nitrogen, phosphorus, etc.), with the remainder of the atoms being carbon atoms.
  • heteroalkyl groups include, but are not limited to, alkoxy, poly(ethylene glycol)-, alkyl- substituted amino, tetrahydrofuranyl, piperidinyl, morpholinyl, etc.
  • alkenyl and alkynyl refer to unsaturated aliphatic groups analogous to the alkyl groups described above, but containing at least one double or triple bond respectively.
  • heteroalkenyl and heteroalkynyl refer to alkenyl and alkynyl groups as described herein in which one or more atoms is a heteroatom (e.g., oxygen, nitrogen, sulfur, and the like).
  • aryl refers to an aromatic carbocyclic group having a single ring (e.g., phenyl), multiple rings (e.g., biphenyl), or multiple fused rings in which at least one is aromatic (e.g., 1,2,3,4-tetrahydronaphthyl, naphthyl, anthryl, or phenanthryl), all optionally substituted.
  • "Heteroaryl” groups are aryl groups wherein at least one ring atom in the aromatic ring is a heteroatom, with the remainder of the ring atoms being carbon atoms.
  • heteroaryl groups include furanyl, thienyl, pyridyl, pyrrolyl, N lower alkyl pyrrolyl, pyridyl N oxide, pyrimidyl, pyrazinyl, imidazolyl, indolyl and the like, all optionally substituted.
  • amine and “amino” refer to both unsubstituted and substituted amines, e.g., a moiety that can be represented by the general formula: N(R')(R")(R" ') wherein R', R", and R" ' each independently represent a group permitted by the rules of valence.
  • acyl As can be represented by the general formula:
  • W is H, OH, O-alkyl, O-alkenyl, or a salt thereof.
  • W is O-alkyl
  • the formula represents an "ester.”
  • W is OH
  • the formula represents a "carboxylic acid.”
  • the oxygen atom of the above formula is replaced by sulfur
  • the formula represents a "thiolcarbonyl” group.
  • W is a S-alkyl
  • the formula represents a "thiolester.”
  • W is SH
  • the formula represents a "thiolcarboxylic acid.”
  • W is alkyl
  • the above formula represents a "ketone” group.
  • W is hydrogen
  • the above formula represents an "aldehyde” group.
  • heterocycle refers to a monocyclic or polycyclic heterocyclic ring that is either a saturated ring or an unsaturated non- aromatic ring.
  • the heterocycle may include 3-membered to 14-membered rings.
  • 3-membered heterocycle can contain up to 3 heteroatoms, and a 4- to 14-membered heterocycle can contain from 1 to about 8 heteroatoms.
  • heteroatom can be independently selected from nitrogen, which can be quaternized; oxygen; and sulfur, including sulfoxide and sulfone.
  • heterocycle or “ heterocyclyl” may include hetero aromatic or heteroaryl groups, as described more fully below.
  • the heterocycle may be attached via any heteroatom ring atom or carbon ring atom.
  • heterocycles include morpholinyl, thiomorpholinyl, pyrrolidinonyl, pyrrolidinyl, piperidinyl, piperazinyl, hydantoinyl, valerolactamyl, oxiranyl, oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, tetrahydropyrindinyl, tetrahydropyrimidinyl, tetrahydrothiophenyl, tetrahydrothiopyranyl, and the like.
  • a heteroatom may be substituted with a protecting group known to those of ordinary skill in the art, for example, the hydrogen on a nitrogen may be substituted with a tert- butoxycarbonyl group.
  • the heterocyclyl may be optionally substituted with one or more substituents (including without limitation a halogen atom, an alkyl radical, or aryl radical).
  • heteroaromatic or “heteroaryl” means a monocyclic or polycyclic heteroaromatic ring (or radical thereof) comprising carbon atom ring members and one or more heteroatom ring members (such as, for example, oxygen, sulfur or nitrogen).
  • the heteroaromatic ring has from 5 to about 14 ring members in which at least 1 ring member is a heteroatom selected from oxygen, sulfur, and nitrogen.
  • the heteroaromatic ring is a 5 or 6 membered ring and may contain from 1 to about 4 heteroatoms.
  • the heteroaromatic ring system has a 7 to 14 ring members and may contain from 1 to about 7 heteroatoms.
  • heteroaryls include pyridyl, furyl, thienyl, pyrrolyl, oxazolyl, imidazolyl, indolizinyl, thiazolyl, isoxazolyl, pyrazolyl, isothiazolyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, triazolyl, pyridinyl, thiadiazolyl, pyrazinyl, quinolyl, isoquinolyl, indazolyl, benzoxazolyl, benzofuryl, benzothiazolyl, indolizinyl, imidazopyridinyl, isothiazolyl, tetrazolyl, benzimidazolyl, benzoxazolyl, benzothiazolyl, benzothiadiazolyl, benzoxadiazolyl, carbazolyl, indolyl, tetrahydroindo
  • substituted is contemplated to include all permissible substituents of organic compounds, “permissible” being in the context of the chemical rules of valence known to those of ordinary skill in the art.
  • substituted may generally refer to replacement of a hydrogen with a substituent as described herein.
  • substituted does not encompass replacement and/or alteration of a key functional group by which a molecule is identified, e.g., such that the "substituted" functional group becomes, through substitution, a different functional group.
  • a "substituted phenyl” must still comprise the phenyl moiety and cannot be modified by substitution, in this definition, to become, e.g., a heteroaryl group such as pyridine.
  • the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and nonaromatic substituents of organic compounds.
  • Illustrative substituents include, for example, those described herein.
  • the permissible substituents can be one or more and the same or different for appropriate organic compounds.
  • heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valencies of the heteroatoms.
  • This invention is not intended to be limited in any manner by the permissible substituents of organic compounds.
  • substituents include, but are not limited to, alkyl, aryl, aralkyl, cyclic alkyl, heterocycloalkyl, hydroxy, alkoxy, aryloxy, perhaloalkoxy, aralkoxy, heteroaryl, heteroaryloxy, heteroarylalkyl, heteroaralkoxy, azido, amino, halogen, alkylthio, oxo, acyl, acylalkyl, carboxy esters, carboxyl, carboxamido, nitro, acyloxy, aminoalkyl, alkylaminoaryl, alkylaryl, alkylaminoalkyl, alkoxyaryl, arylamino, aralkylamino, alkylsulfonyl, carboxamidoalkylaryl, carboxamidoaryl, hydroxyalkyl, haloalkyl, alkylaminoalkylcarboxy, aminocarboxamidoalkyl, alk,
  • C 6 o was purchased from SES Research.
  • PC 6 iBM and P3HT were purchased from Sigma-Aldrich.
  • PEDOT/PSS were purchased from Ossila.
  • 3,6-Di-2- pyridyl-l,2,4,5-tetrazine was purchased from Alfa Aesar. All the compounds purchased from commercial sources were used as received.
  • Other materials including solvents and electrolyte salt were commercially available.
  • Anhydrous solvents were obtained from a solvent purification system (Innovative Technologies). Measurements. Reaction mixtures containing multiadducts of fullerenes were separated by 5PBB Cosmosil column (10 mm x 250 mm) from Nacalai Tesque, Inc. installed in Agilent Technologies ProsStar 210 High Pressure Liquid Chromatography
  • a Pt button (1.6 mm in diameter) electrode, a Pt wire, and a quasi-internal Ag wire submerged in 0.01M AgNO 3 /0.1M tetrabutylammonium hexafluorophosphate (TBAPF 6 ) in acetonitrile were used as a working electrode, a counter electrode, and a reference electrode, respectively, in 0.1M TBAPF 6 toluene/acetonitrile (4: 1) solution.
  • the ferrocene/ferrocenium (Fc/Fc + ) redox couple was used as an internal standard, with the half-wave potentials observed between 0.193-0.205 V vs Ag/Ag + in toluene/acetonitrile (4: 1) solution.
  • Differential Scanning Calorimetry (DSC) was measured on a TA Instruments Q1000 DSC at scan rate of 10° C/min over the range of 25° C to 200° C or 35° C to 200° C.
  • isobenzofulvene reagent relative to C 6 o at low temperatures (e.g., 0 °C to room temperature).
  • the reaction mixture consisted of monoadduct with bisadduct.
  • the major product, isobenzofulvene monoadduct (IBF-Mono) was easily purified via silica column chromatography with the elution of CS 2 /hexane solvent mixture.
  • the yield of the bisadducts (IBF-Bis) increased when the isobenzofulvene reacted with IBF-Mono instead of C 6 o as a dienophile. (FIG. IB).
  • the bisadducts were comprised of multiple regioisomers, as observed by NMR, and exhibited enhanced solubility relative to the mono-adduct in many organic solvents including dichloromethane, chloroform, toluene, and o-dichlorobenzene.
  • the bis-adduct was purified by HPLC using a 5PBB Cosmosil column with toluene elution. With 56 pi electrons, the bisadducts were expected to possess elevated LUMO energy levels and higher VOC compared to those of the monoadducts, as observed for other fullerene bisadducts. Epoxidation of the monoadduct was successfully conducted and generated a product (IBF-Ep) as shown in FIG. 2C.
  • IBF-Ep showed increased solubility in organic solvents compared to that of IBF-Mono, due at least in part to higher polarity imparted by the epoxide oxygen.
  • Epoxide derivatives of IBF-Bis were also synthesized, with one or two epoxidized isobenzofulvene moieties in order to take advantage of high VOC characteristics of the 56 pi electron system and to observe the effect of epoxide groups on JSC. (FIGS.
  • IBF-Bis-Epl was synthesized by adding an isobenzofulvene addend to IBF-Ep scaffold, and IBF- Bis-Ep2 was prepared by the complete epoxidation of IBF-Bis.
  • the compound was prepared according to a modified version of the procedure described in Lombardo, L.; Wege, D.; Wilkinso.Sp Aust J Chem 1974, 27, 143.
  • a refluxing solution of 6,6-dimethylfulvene (5.00 g, 5.7 mL, 47 mmol) and isoamyl nitrite (8.3 g, 9.5 mL, 71 mmol) in 1,2-dichloroethane (40 mL) was added dropwise a solution of anthranilic acid (9.7 g, 71 mmol) in 30 mL acetone.
  • the mixture was then refluxed for 90 minutes before removing the solvents under reduced pressure and extracting with boiling hexanes.
  • ITO indium tin oxide
  • PEDOT:PSS layer PEDOT:PSS (2-5 wt% in water, Aldrich) was spin-coated at 4000 rpm and annealed at 150 0 C (using a hotplate) for 20 min under nitrogen.
  • a 25 mg/mL solution of 1: 1 P3HT:fullerene in chlorobenzene (CB) was spin- coated onto the PEDOT:PSS layer at 1000 rpm under nitrogen and annealed on a 150 0 C hotplate for 20 min under nitrogen. Finally 25 nm Ca followed by 100 nm Al electrode was deposited by thermal evaporation.
  • the light intensity was calibrated using a Newport silicon photodetector (for wavelength of 400-800 nm), and the photocurrent at a short-circuit condition was measured with a Stanford Research SR830 lock-in amplifier.
  • Transient photocurrents and recombination lifetime measurement conducted with a Newport laser diode (830 nm) driven by an Agilent 33220A function generator was used as a second light source to provide square wave modulated illumination. This illumination was filtered through a neutral density filter before reaching the device to ensure a small illumination perturbation.
  • Voc decay transients were recorded on a Tektronix TDS 3054B digital oscilloscope.
  • Cyclic voltammetry was conducted to measure the relative reduction potentials of the C 6 o derivatives in Examples 2-6 under anhydrous, air-free conditions with ferrocene/ferrocenium (Fc/Fc+) internal standard.
  • ferrocene/ferrocenium Fc/Fc+
  • 0.1 M TBAPF 6 toluene/acetonitrile (4: 1) solution four reversible redox peaks were exhibited for each compound, and the relative positions of the onset reduction potentials were used to compare the LUMO energy levels of the fullerenes.
  • FIG. 3 shows cyclic voltammograms for (a) PCBM, IBF-Mono, and IBF-Bis; (b) PCBM, IBF-Mono, and IBF-Ep; and (c) PCBM, IBF-Bis, IBF-Bis-Epl, and IBF-Bis-Ep2 (under nitrogen, 0.1M Bu 4 NPF 6 in toluene/acetonitrile (4: 1), Pt (WE), Pt wire (CE), Ag/AgN0 3 (RE), scan rate 0.1 V/s, Fc/Fc + internal standard E 1/2 at 0.20 V).
  • Relative to PCBM the reduction onset potentials of IBF-Mono and IBF-Bis were shifted toward negative potentials by ca.
  • FIG. 5 shows HOMO-LUMO energy diagrams for the functionalized fullerenes, with MO energy levels scaled relative to the vacuum level set to zero. Increasingly negative reduction potentials corresponded to raised LUMO levels, increasing the effective band gap and VOC of BHJ solar cells.
  • the pi-pi interaction between the C 6 o surface and the attached functional groups e.g., the aromatic ring and the double bond of the isobenzofulvene groups
  • Epoxidation of IBF-Mono essentially removed the pi-pi interaction between C 6 o and the double bond of isobenzofulvene moiety, resulting in a slight increase in reduction potentials for IBF-Ep relative to those of IBF-Mono.
  • FIG. 3A This may be attributed at least in part to the combined effects of the reduced pi-pi interaction and the presence of the electron-withdrawing epoxide group. Similar phenomena were observed for the epoxide derivatives of IBF-Bis.
  • FIG. 3C the redox behaviors of IBF-Bis, IBF-Bis-Epl, and IBF-Bis-Ep2 were plotted relative to PCBM.
  • UV-Vis spectroscopy was employed to study the optical properties of substituted fullerenes in solution state, since the absorption of visible light by the acceptors can contribute to the increased JSC of solar cells.
  • the comparative absorption spectra of the C 6 o derivatives in Examples 2-6 and PCBM were plotted over the range of 400-800 nm. FIG.
  • the spikes and the absorption onset wavelengths, o Dset , of the monoadducts were red-shifted from those of PCBM.
  • the bisadducts showed broader absorption characteristics than the monoadducts since they were in the form of regioisomer mixtures, and higher absorptivity was imparted by the lowered symmetry of the fullerenes.
  • Longer onset wavelengths and smaller band gaps were observed for the bisadducts compared to the monoadducts.
  • the band gaps were used to approximate the HOMO energy levels of the fullerenes (e.g., by subtracting band gaps from the LUMO levels derived from cyclic voltammetry).
  • Table 1 The values obtained from the above-mentioned experiments are summarized in Table 1, and the MO energy level diagrams of the fullerenes are depicted in FIG. 5.
  • IBF-Mono, IBF-Bis, IBF-Ep, IBF-Bis-Epl, and IBF-Bis-Ep2 were used as electron acceptors in BHJ solar cells with a P3HT donor, and their performances were compared to conventional P3HT:PCBM devices. Experimental details of device fabrication can be found in Example 7. FIG.
  • FIG. 6 shows (a) the current density as a function of applied voltage for the fullerenes in BHJ architecture for solar cells with P3HT as an electron donor, compared to conventional P3HT:PCBM, and (b) a box plot of the VOC values obtained from the devices in (a) where the whiskers were the 10th to 90th percentile and the box was the 25th and 75th percentile containing a median and average (dotted line).
  • the relative parameters for FIG. 6 are listed in Table 2.
  • thin films and devices were studied using steady- state spectroscopy.
  • the thin films were fabricated under the same conditions as used for the devices in FIG. 3A.
  • FIG. 7 A shows steady-state spectral UV-vis absorption spectra and FIG. 7B shows steady-state spectral photoluminescence emission of thin film, for various fullerene adducts.
  • the thin films were excited with monocromator light at 500nm and normalized for absorption. All fullerene adducts exhibit quenched photoluminescence (PL) when blended with P3HT, except for IBF-Mono which involved high level of radiative exciton recombination. Such recombination may contribute to the low JSC observed for P3HT:IBF-Mono devices.
  • FIG. 7C shows the Spectral External Quantum Efficiency (EQE) of the devices.
  • EQE Spectral External Quantum Efficiency
  • P3HT:IBF-Mono devices exhibited the lowest EQE observed among the devices in this example, followed by the P3HT:IBF-Bis device. Epoxidation of the IBF-Mono and Bis resulted in devices which exhibited higher EQE, as reflected in the JSC values.
  • FIG. 7D shows the Spectral Internal Quantum Efficiency (IQE) obtained by normalizing the EQE by the absorption.
  • P3HT:IBF-Ep devices exhibited the highest IQE and thus the highest JSC among the devices in this example.
  • IBF-Bis-Ep2 devices showed similar performance as the IBF-Bis-Epl device. From steady-state UV-Vis absorption of thin films plotted in FIG.
  • P3HT:IBF-Mono devices exhibited high radiative recombination, as shown in the steady- state photoluminescence (PL) emission spectra in FIG. 7B.
  • Quenching of the PL emission of the electron donor in BHJ reflected efficient charge transfer from the donor to the acceptor. Quenched emission was observed in all BHJ blends except for P3HT:IBF-Mono, which indicated high rates of radiative exciton-recombination in P3HT:IBF-Mono films.
  • Such high recombination may contribute to the low JSC of P3HT:IBF-Mono devices.
  • the topography images of atomic force microscopy (AFM) at ⁇ scale indicate the suboptimal phase separations of P3HT and IBF-Mono domains (as opposed to
  • P3HT:PCBM devices possibly induced by the low solubility of IBF-Mono.
  • Example 12 Transient Measurements Transient Photovoltage (TPV) and photocurrent (TPC) are routinely employed to assess charge carrier recombination at an open circuit and to relate the amplitude of VOC to charge carrier recombination dynamics. Recombination lifetime at an open circuit was measured as a function of the excess charge carrier density.
  • FIG. 9 shows transient photocurrents at short circuit of P3HT:PCBM and P3HT:IBF-Ep devices, suggesting that mobility might be higher in P3HT:PCBM devices.
  • P3HT:PCBM devices exhibit the shortest recombination lifetime compared to other devices at the same averaged excess charge density.
  • IBF-C6o-based devices are characterized by similar recombination dynamics, which suggests their distinct electronic behavior at the interface with P3HT, compared to PCBM.
  • differences in VOC can be attributed at least in part to differences in LUMO energy, as shown in FIGS. 5-6 and Tables 1 and 2, except for P3HT:IBF-Mono.
  • the low reproducibility of P3HT:IBF-Mono led to large variation of VOC values and low median VOC.
  • the slower recombination dynamics caused by the improved electronic interface behavior between IBF-C60 derivatives and P3HT could induce the generation of large VOC for the corresponding devices.
  • FIG. 10 shows recombination lifetime as a function of the averaged excess charge density measured with transient photovoltage and photocurrent (TPV/TPC).
  • P3HT:PCBM devices exhibit the fastest recombination lifetime compared at the same averaged excess charge density.
  • the slower recombination of P3HT:IBF-Ep devices leads to the larger Voc relative to P3HT:PCBM devices.
  • IBF-C6o-based devices are characterized by similar recombination rates, suggesting their similar electronic behavior at the interface with P3HT.
  • the different Voc values observed may be influenced by the differences in LUMO energy level.
  • Solar cells were fabricated having the following structure (an "inverted” structure): Glass/ITO/ZnO/polymer:IBF-Ep/Al/Mo0 3 /Ag. Prior to use, the patterned ITO-coated glass substrates were cleaned with detergent and water, then ultrasonicated in acetone and isopropyl alcohol for 15 min each. The ZnO layer was deposited by spin- coating according to the method described in Po et al., "From lab to fab: how must the polymer solar cell materials design change? - an industrial perspective," Energy
  • a 10 nm M0O 3 buffer layer and a 100 nm aluminum layer were deposited by vacuum deposition.
  • the photovoltaic parameters were measured using a shadow mask of 16 mm .
  • the device electrical characterization was carried out at room temperature in glove-box. Solar cells were illuminated using a solar simulator (Sun 2000, Abet Technologies) and the light power intensity was calibrated at AM 1.5 illumination conditions (100 mW cm " ) using a certified KG-5 filtered silicon solar cell.
  • the current- voltage curves were taken with a Keithley 2602 source-measure.
  • Table 3 shows a summary of the photovoltaic parameters for the devices in this example.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Nanotechnology (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Inorganic Chemistry (AREA)
  • Photovoltaic Devices (AREA)
  • Hybrid Cells (AREA)
PCT/US2015/026379 2014-04-18 2015-04-17 Functionalized nanostructures and devices including photovoltaic devices WO2015161203A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US15/305,076 US10672988B2 (en) 2014-04-18 2015-04-17 Functionalized nanostructures and devices including photovoltaic devices
EP15780617.5A EP3132451A4 (en) 2014-04-18 2015-04-17 Functionalized nanostructures and devices including photovoltaic devices
CN201580032244.0A CN106463196B (zh) 2014-04-18 2015-04-17 官能化纳米结构和包括光伏器件的器件

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201461981552P 2014-04-18 2014-04-18
US61/981,552 2014-04-18

Publications (1)

Publication Number Publication Date
WO2015161203A1 true WO2015161203A1 (en) 2015-10-22

Family

ID=54324613

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2015/026379 WO2015161203A1 (en) 2014-04-18 2015-04-17 Functionalized nanostructures and devices including photovoltaic devices

Country Status (4)

Country Link
US (1) US10672988B2 (zh)
EP (1) EP3132451A4 (zh)
CN (1) CN106463196B (zh)
WO (1) WO2015161203A1 (zh)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI759815B (zh) * 2019-08-15 2022-04-01 國立清華大學 彈性導電柱體、製造方法及使用其的探針卡

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090202921A1 (en) * 2008-02-12 2009-08-13 Fujifilm Corporation Optical recording composition and holographic recording medium
US20100179054A1 (en) * 2008-12-12 2010-07-15 Massachusetts Institute Of Technology High charge density structures, including carbon-based nanostructures and applications thereof
EP2472656A2 (en) * 2008-08-15 2012-07-04 Massachusetts Institute of Technology Layer-by-layer assemblies of carbon-based nanostructures and their applications in energy storage and generation devices
US20130089790A1 (en) * 2011-10-11 2013-04-11 Hye Ryung Byon Carbon Electrodes

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101529610B (zh) 2006-06-13 2013-01-02 普雷克托尼克斯公司 包含富勒烯及其衍生物的有机光伏器件
KR101535696B1 (ko) 2008-02-05 2015-07-09 바스프 에스이 릴렌-(π-억셉터) 공중합체로부터 제조된 반도체 재료
WO2010135701A1 (en) 2009-05-21 2010-11-25 Polyera Corporation Conjugated polymers and their use in optoelectronic devices
TWI518106B (zh) * 2010-12-21 2016-01-21 住友化學股份有限公司 具有碳簇構造之高分子化合物及使用該化合物之有機裝置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090202921A1 (en) * 2008-02-12 2009-08-13 Fujifilm Corporation Optical recording composition and holographic recording medium
EP2472656A2 (en) * 2008-08-15 2012-07-04 Massachusetts Institute of Technology Layer-by-layer assemblies of carbon-based nanostructures and their applications in energy storage and generation devices
US20100179054A1 (en) * 2008-12-12 2010-07-15 Massachusetts Institute Of Technology High charge density structures, including carbon-based nanostructures and applications thereof
US20130089790A1 (en) * 2011-10-11 2013-04-11 Hye Ryung Byon Carbon Electrodes

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP3132451A4 *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI759815B (zh) * 2019-08-15 2022-04-01 國立清華大學 彈性導電柱體、製造方法及使用其的探針卡

Also Published As

Publication number Publication date
EP3132451A4 (en) 2018-01-03
US20170186960A1 (en) 2017-06-29
CN106463196A (zh) 2017-02-22
EP3132451A1 (en) 2017-02-22
US10672988B2 (en) 2020-06-02
CN106463196B (zh) 2019-06-18

Similar Documents

Publication Publication Date Title
US11974500B2 (en) Molecular semiconductors containing diketopyrrolopyrrole and dithioketopyrrolopyrrole chromophores for small molecule or vapor processed solar cells
Wong Luminescent organometallic poly (aryleneethynylene) s: functional properties towards implications in molecular optoelectronics
Ye et al. Application of bis-PCBM in polymer solar cells with improved voltage
CA2880977C (en) Conjugated polymer, and electron donating organic material, material for photovoltaic device and photovoltaic device using the conjugated polymer
CN110268538B (zh) 空穴传输材料和使用该空穴传输材料的光伏装置
US9246110B2 (en) Organic material and photoelectric conversion element
JP2010529219A (ja) 固体電子デバイスにおいて使用するためのポルフィリンおよび導電性ポリマー組成物
Chava et al. Mxene-based tailoring of carrier dynamics, defect passivation, and interfacial band alignment for efficient planar p–i–n perovskite solar cells
Han et al. Cyclobutadiene–C60 Adducts: N‐Type Materials for Organic Photovoltaic Cells with High VOC
Chochos et al. Synthesis of a soluble n-type cyano substituted polythiophene derivative: A potential electron acceptor in polymeric solar cells
JP6904252B2 (ja) コポリマー、光電変換素子、太陽電池及び太陽電池モジュール
Chen et al. A non-fullerene acceptor with all “A” units realizing high open-circuit voltage solution-processed organic photovoltaics
Liu et al. Low-bandgap small-molecule donor material containing thieno [3, 4-b] thiophene moiety for high-performance solar cells
Mori et al. Alkoxy-substituted anthra [1, 2-c: 5, 6-c′] bis ([1, 2, 5] thiadiazole)(ATz): a new electron-acceptor unit in the semiconducting polymers for organic electronics
Singh et al. Efficient solution processable polymer solar cells using newly designed and synthesized fullerene derivatives
US9755150B2 (en) Functionalized nanostructures and related devices
JP6300204B2 (ja) 高分子化合物、有機半導体材料、光電変換素子及びトランジスタ
JP5639783B2 (ja) 光電変換素子
KR101553806B1 (ko) 포스핀 옥사이드기를 포함하는 유기 반도체 화합물 및 이를 이용한 유기태양전지
Furukawa et al. High-Crystallinity π-Conjugated Small Molecules Based on Thienylene–Vinylene–Thienylene: Critical Role of Self-Organization in Photovoltaic, Charge-Transport, and Morphological Properties
US10672988B2 (en) Functionalized nanostructures and devices including photovoltaic devices
KR101535066B1 (ko) 두 개의 적층형 유기 태양전지 소자용 유기 반도체 화합물, 및 이를 포함하는 유기전자소자
EP2729439A1 (en) Two-component electron-selective buffer layer and photovoltaic cells using the same
JP6995596B2 (ja) 光電変換素子
Mak et al. Optically tunable intramolecular charge transfer dyes for vacuum deposited bulk heterojunction solar cells

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 15780617

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

WWE Wipo information: entry into national phase

Ref document number: 15305076

Country of ref document: US

REEP Request for entry into the european phase

Ref document number: 2015780617

Country of ref document: EP

WWE Wipo information: entry into national phase

Ref document number: 2015780617

Country of ref document: EP